This invention relates to an endoscopic procedure for retrieving objects such as polyps from inside patients. This invention also relates to an associated endoscopic instrument assembly.
In a conventional polyp retrieval operation, an endoscope is inserted into an internal cavity of a patient, e.g., into the colon, and is used to visually identify and locate the polyp in the internal cavity. Upon the identification of the polyp or other growth which is to be removed, a wire extending through a tube in the biopsy channel of the endoscope is slid in the distal direction so that a cauterization loop connected to the wire is ejected from the distal end of the tube and the endoscope. The loop and the endoscope are manipulated from outside of the patient to pass the loop over the polyp or growth. The wire is then withdrawn in the proximal direction to tighten the loop around a base region or neck of the polyp. Once the loop is in contact with the base region of the polyp, an electrical current is conducted through the loop via the wire. Generally, as the loop is closed about the base region of the polyp, electrical current is transmitted through the narrowed organic tissues and thereby generates therein heat sufficiently great to cut and cauterize.
Once a polyp is severed by such a snare cauterization technique, it frequently becomes difficult to capture the polyp and retrieve it from the patient. Sometimes the cauterization loop is used in an effort to ensnare the polyp. Other capture techniques involve the use of forceps or the application of suction. In using forceps, the snare cauterization tube is removed from the biopsy channel of the endoscope and replaced with the forceps. In using suction, a vacuum is applied via a suction channel of the endoscope.
No matter which specific technique is used, the polyp frequently escapes from the capturing instrumentality and falls away into the colon (or other cavity). Especially in cases where the polyp is large, the effort and time expended in retrieving the severed polyp may rival or even exceed the effort and time required to locate and sever the polyp. In extreme cases, the endoscope must be removed without the polyp and the patient given an enema in an attempt to flush out the polyp from the colon.
Furthermore, there are numerous cases where a severed polyp is never recovered. Sometimes, the polyp is masserated during the retrieval attempt. In all such cases, the pathologist is unable to determine whether the polyp contains carcinoma in situ (localized) or infiltrative carcinoma (spread). The patient must then undergo a colon ressection, sometimes unnecessarily.
In any event, the manipulations necessary to remove a severed polyp generally increase the trauma to the patient, the expense of the surgery and the hospitalization time. There is now a long-felt need to improve the snare cauterization technique to facilitate the capture and retrieval of severed polyps.
U.S. Pat. Nos. 5,201,740 and 5,190,542 to Nakao and Wilk disclose a cauterization loop with an attached capture pocket. Such a snare assembly represents a significant advance in the art and evidently solves all of the problems inherent in polyp retrieval. However, it appears that there is some rooom in the industry for an alternative method for snare retrieval.